ExploitedNot in CISA KEV yet

CVE-2025-34027

Versa Concerto Authentication Bypass File Write Remote Code Execution

Exploitation confirmed. First attested on 2025-07-21 by GCVE · kevintel, GCVE · shadowserver.

Published2025-05-21
WeaknessCWE-367

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

The Versa Concerto SD-WAN orchestration platform is vulnerable to an authentication bypass in the Traefik reverse proxy configuration, allowing at attacker to access administrative endpoints. The Spack upload endpoint can be leveraged for a Time-of-Check to Time-of-Use (TOCTOU) write in combination with a race condition to achieve remote code execution via path loading manipulation, allowing an unauthenticated actor to achieve remote code execution (RCE).This issue is known to affect Concerto from 12.1.2 through 12.2.0. Additional versions may be vulnerable.

Timeline

dates in UTC

2025-05-2122:15CVE publishedNVD
2025-07-2120:43Listed as exploited by GCVEGCVE

Observed activity

isMalicious corpus · updated 2026-10-23 15:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-34027?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-34027?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Versa-networks concerto

Branch	Affected	Fixed in	Source
12.1	≥ 11.4.0, ≤ 12.1.1	no fix published	NVD
12.1	= 12.1.2	no fix published	NVD
12.2	= 12.2.1	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

GCVEexploitation2026-06-21
CISA-ADPSSVC decisionnone2025-05-28
OpenCVESSVC decisionnone—
CNACVSS 4.010read 2026-10-23
NVDCVSS 3.19read 2026-10-23
CNAweakness (CWE)CWE-367read 2026-10-23
FIRST EPSSEPSS score46.1 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS 4.0 vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published: 2025-05-21
Last Modified: 2026-08-25
NVD status: Analyzed

Frequently asked questions

What is CVE-2025-34027?

Is CVE-2025-34027 actively exploited?

Active exploitation of CVE-2025-34027 has not been confirmed. Its EPSS score was 46.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-34027?

CVE-2025-34027 has a CVSS v3 base score of 9 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

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